In general, a video switcher allows you to switch from one video input signal to another. Input signals, also called “input sources” or “sources,” are signals sent to the switcher from cameras, video players, and other video equipment. Thus the video switcher is a powerful tool for television production. The switcher receives multiple video input signals, processes those signals, and then outputs the processed video. Efficient real time switcher-operation is essential for live production, and can save valuable time in post-production as well. With the advent of digital electronics, video switchers have been developed that act on digitized video signals whereby processing capabilities have been improved. Additionally, it has become commonplace to incorporate into video images digital effects which, due to advanced digital processing, have become more complex and elaborate.
Today switchers may utilize video processing units having the capability to perform video processing and video image effects. These video processing units are most often mix/effects processors (M/Es), but can also be a digital picture manipulator (DPMs), a digital video effects (DVE) unit, video stores, or still stores. A video processing unit is generally shown as video processor 105 in FIG. 1. Also shown in FIG. 1 is an M/E 104, however as pointed out above, the video processor 105 can be an M/E, DPM, DVE or some other video processor.
A video processor such as an M/E typically has exceptional capabilities including two-dimensional compression and three-dimensional transformation of video images, as well as the ability to position a digitally altered video signal anywhere in a background signal.
Known switchers also create effects such as wipes, dissolves and keys. For example, a switcher can change scenes by “wiping” from one scene to another, or by dissolving one scene into another directly, or via a neutral, e.g., black, background. Additionally, a switcher can mix the output of a character generator, for example, with a background input, thereby “layering” text on top of the background in accordance with a particular key signal, e.g., a self key, luminance key or a preset pattern key. Known switchers can take virtually any input signal and layer that signal on virtually any background.
FIG. 1 illustrates a video switcher 100 useful in explaining the present invention. The internal structure of a video switcher (aka vision mixer) generally consists of a video routing matrix 102 of crosspoints plus one or more video processing units (104, 105), which, as pointed out above, is video equipment that performs digital effects such as compression and transformation and are most often M/Es 104, but can also be DVEs or DPMs, video stores, or still stores, etc.
Primary inputs 106 to video switcher 100 are connected as inputs to the switcher's routing matrix 102. The inputs may be from any video source, for example cameras, video players, and other video equipment. The outputs from the routing matrix 102 can include auxiliary outputs 110, primary outputs 108, and outputs routed to the processing units (104, 105).
As shown in FIG. 1, the outputs from the processing units (104, 105) are sent back (see re-entered inputs 107) as inputs to the routing matrix 102. Thus, the re-entered inputs 107 may be switched to the primary outputs 108, which are then taken as outputs from the routing matrix 102. In some switchers (not shown in FIG. 1) the primary outputs come directly from the processing units (104, 105).
Typically primary outputs 108 are pre-assigned to primary inputs 106 and/or the re-entered inputs 107. Primary outputs 108 are normally used for live production (primary TV feeds), whereas auxiliary outputs 110 are typically used for secondary purposes. For example, an auxiliary bus output may be used to feed studio monitors, provide feeds to other locations, or provide feeds for engineering confidence monitoring. In recent years auxiliary bus outputs have been used to feed monitors placed into the “on-air set” in a TV studio (possibly a news or weather broadcast where the monitor receiving the source is used as part of the TV broadcast). Auxiliary outputs typically have direct interface buttons on the video switcher control panel, which allows the operator to control the video feed to the auxiliary outputs, thus allowing for user interaction and quick changes. Additionally, many installations have remote auxiliary bus control panels, so that users other than the main video switcher operator can control the source selection on a particular auxiliary bus.
Although the output on an auxiliary bus can be ‘switched’ from one source to another using the routing matrix, in current implementations this “switching” has typically been limited to simple cuts. For example, a nearly instantaneous switch from one picture to another (i.e. one source to another source). This switch is performed without glitch during the vertical blanking period of a video field or frame. The current source can be one of the primary inputs 106 and the new source, to which to an operator switches to, can likewise be a primary input 106. This cut can by performed by changing the crosspoint in the routing matrix from one source to another.
Because the uses for auxiliary buses are increasing and it is now common for auxiliary buses to feed display devices such as plasma screens which are placed into the “on-air sets” these displays are now part of the on-air look, thus there is a desire from TV producers to improve production values by having more complex transitions and effects on these “on-air” displays. For example there is a desire for effects on these displays beyond simple cuts, such as, dissolves, wipes, mixes, or background DPM transitions. Thus, there is a need for having video processing units available for the auxiliary buses for use in providing transitional effects. For example, having M/Es, M/Es with internal DPMs, or DPMs available for providing effects for the auxiliary bus.
Indeed, performing such transition effects such as dissolves and wipes is one of the reasons that M/Es were originally created. Nowadays, video switchers have generally 1 to 5 M/Es. The U.S. patent to Kevin D. Windrem (U.S. Pat. No. 6,281,941) titled “Mix-effect bank with multiple programmable outputs,” herein incorporated by reference, teaches effectively doubling the number of M/Es by giving each M/E the potential for a primary and secondary partition. As a consequence, Windrem's invention effectively increased the number of primary outputs from the switcher; a primary output being nearly always having its output derived from an M/E output.
For auxiliary buses and outputs, Windrem's concept describes a simple way to have more transition effects by simply adding more M/Es. However, M/Es are complex and expensive and over time, M/Es will continue to become more and more complex. Thus, it is not feasible to add an M/E for each of the auxiliary buses. For example there may be switches with 32 auxiliary buses and they may have a routing matrices of, for example, 128×128. The trend is to larger and larger sizes in the future.
Other prior art approaches teach, rather than simply adding more M/Es, using simplified ‘lightweight’ M/Es which can be variously named as light or mini M/Es or auxiliary bus effects processors. For example, providing a simple mixer with two inputs in each auxiliary bus. This solution can be extended by adding third and fourth inputs to key signals (such as video bugs) over the background. However, with the ‘lightweight’ M/Es there is still the problems of adding complexity and cost into the switcher.
Thus the prior art generally teaches adding more and more M/Es, DPMs, etc. into switches or using very limited M/Es, however this results in either having a massive duplication of these mixing resources in each auxiliary bus, or the feature is limited and inflexible and only works with certain auxiliary buses. Thus, there is a desire for a video switcher to flexibly provide transition effects on the video switcher's auxiliary buses, while minimizing the complexity of the video switcher.
Whatever the precise merits, features, and advantages of the above-mentioned prior art techniques, none of them achieve or fulfill the purposes of the present invention.